New Endohedral Fullerenes Containing Uranium

In 1992, Smalley et al reported (Science 1992, 257, 1661) the mass spectral detection of a family of endohedral fullerene compounds containing uranium inside the carbon cages. These series included: U@C₅₈, U@C₆₀, U@C₆₈, U₂@C₅₀, U@C₇₀, U₂@C₅₂, U@C₇₂, U₂@C₅₈, and U₂@C₆₀, but none of these compounds were isolated or otherwise characterized. In 2007, Lu et al reported theoretical calculations for U₂@C₆₀ and predicted that the encapsulated uranium dimer would exhibit a sextuple metal-metal bond. We have succeeded in producing, detecting and partially isolating a totally new family of endohedral uranium-containing fullerenes, including: U₂C₇₈, U₂C₇₉, U₂C₈₀ and U₂C₈₁, see attached figure for the corresponding MALDI. The synthesis, purification and partial characterization of these new endohedral compounds will be presented and discussed.